1. Industrial Field of Use
This invention relates to a clamping apparatus for use in lifting objects such as cases of soft drink cans or bottles. More particularly, it relates to a clamping apparatus capable of lifting an entire layer of objects from a pallet.
2. Description of the Related Art
Soft drink cans and bottles are commonly shipped from factories in cardboard cases stacked on wooden pallets, which can be lifted with a fork lift. Each pallet contains a plurality of layers each containing a plurality of cases of a single type of product. For example, ten or more layers of cases may be stacked atop a single pallet.
Retailers of soft drinks frequently order less than one entire pallet of a type of soft drink. For example, a retailer may desire a half pallet of orange soda, a quarter pallet of grape soda, and a quarter pallet of ginger ale. Therefore, before soft drinks are shipped to a retailer, they are unloaded by a distributor from pallets containing a single variety and repacked as pallets containing a plurality of different varieties of soft drinks.
The process of unloading and reloading pallets of soft drink cases is usually done by hand. This is monotonous and arduous work, and often results in physical injuries to the laborers who do this work. Furthermore, manual transfer of cases between pallets is a slow process, and a typical worker can unload and reload no more than 500 cases of soft drink cans per hour. This same problem exit with many other types of products, which are shipped from factories in lots too large for a single retailer to use.
Clamping devices for use with fork lifts have been developed which can lift an entire layer of objects (such as bricks) at a time from a pallet and move the layer to a different pallet. These devices typically have four clamping arms which pivot about horizontal axes to clamp a layer from four directions at once. The clamping arms, with the layer of bricks or other objects held therebetween, can then be transferred to a new location by a fork lift. However, these conventional clamping devices are all designed for lifting layers having specific fixed dimensions and are not suitable for lifting layers of variable dimensions. For example, if a clamping device designed for lifting a perfectly square layer is used to lift an elongated rectangular layer, two of the clamping arms will grasp the layer at a different height from the other two clamping arms.
With some objects, this difference in height may not be a problem. However with cases of soft drinks, for example, a difference of a few inches between the heights where the clamping arms contact the different sides of the layer can make it impossible for the clamping arms to lift the layer. Accordingly, there is a need for a clamping apparatus which can be used to lift both square objects and elongated rectangular objects while holding all four sides of the objects at substantially the same height.